U.S. patent application number 15/213955 was filed with the patent office on 2017-03-02 for engine control device.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Toshio MURATA, Tadashi Nakagawa.
Application Number | 20170058747 15/213955 |
Document ID | / |
Family ID | 58103475 |
Filed Date | 2017-03-02 |
United States Patent
Application |
20170058747 |
Kind Code |
A1 |
MURATA; Toshio ; et
al. |
March 2, 2017 |
ENGINE CONTROL DEVICE
Abstract
The present disclosure provides an engine control device
including: an adjustment section that adjusts a flow amount per
unit time of exhaust gas from an engine; and a control section
that, in a case in which a temperature below freezing point is
detected by a temperature detection section that detects an
external air temperature or an intake air temperature, a preceding
engine operation duration is shorter than a first duration, and a
value in a predetermined range in which water in an exhaust pipe
can be drained by the flow amount being raised by a certain amount
is detected by a value detection section that detects a value
representing an acceleration, an accelerator opening or an engine
rotation speed, controls the adjustment section so as to raise the
flow amount by the certain amount until a second duration has
passed from starting of the engine.
Inventors: |
MURATA; Toshio; (Toyota-shi,
JP) ; Nakagawa; Tadashi; (Miyoshi-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOYOTA JIDOSHA KABUSHIKI KAISHA |
Toyota-shi |
|
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi
JP
|
Family ID: |
58103475 |
Appl. No.: |
15/213955 |
Filed: |
July 19, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01N 2240/02 20130101;
F01N 3/005 20130101; F01N 2570/22 20130101; F01N 2900/1411
20130101; F01N 9/00 20130101; F01N 5/02 20130101; F01N 2900/12
20130101; F01N 2430/00 20130101; Y02T 10/12 20130101; F01N 2590/11
20130101; F01N 2900/102 20130101; Y02T 10/40 20130101; Y02T 10/16
20130101; Y02T 10/47 20130101; Y02T 10/20 20130101 |
International
Class: |
F01N 9/00 20060101
F01N009/00; F01N 5/02 20060101 F01N005/02; F01N 3/00 20060101
F01N003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 2015 |
JP |
2015-165730 |
Claims
1. An engine control device comprising: an adjustment section that
adjusts a flow amount per unit time of exhaust gas exhausted from
an engine; and a control section that, in a case in which a
temperature below freezing point is detected by a temperature
detection section that detects an external air temperature or an
intake air temperature, a preceding engine operation duration is
shorter than a pre-specified first duration, and a value in a
predetermined range in which water in an exhaust pipe can be
drained by the flow amount being raised by a certain amount is
detected by a value detection section that detects a value
representing an acceleration, an accelerator opening or an engine
rotation speed, controls the adjustment section so as to raise the
flow amount by the certain amount until a pre-specified second
duration has passed from starting of the engine.
2. The engine control device according to claim 1, wherein: the
adjustment section adjusts the flow amount per unit time of exhaust
gas by adjusting the engine rotation speed, the control section
includes a charging control section that, in a case in which a
charge amount of a battery, in a hybrid vehicle that is equipped
with an engine and a motor-generator as drive sources for running,
is below a pre-specified threshold, controls charging of the
battery such that the motor-generator is driven by motive power of
the engine and charges the battery, and the control section
controls the charging control section so as to charge the battery
with motive power corresponding to a rise in the engine rotation
speed that is produced by the control of the adjustment section to
raise the flow amount by the certain amount.
3. The engine control device according to claim 2, wherein: the
charging control section ends the charging of the battery in a case
in which the charge amount of the battery reaches at least a
pre-specified reference value, and the control section, in a case
in which adjusting the flow amount of exhaust gas, alters the
reference value and controls the charging control section.
4. The engine control device according to claim 1, wherein: the
adjustment section adjusts the flow amount per unit time of exhaust
gas by adjusting the engine rotation speed, and the control section
controls a consumption section that is for consuming motive power
corresponding to a rise in the engine rotation speed so as to
consume motive power corresponding to a rise in the engine rotation
speed that is produced by the control of the adjustment
section.
5. The engine control device according to claim 1, further
comprising an exhaust heat recovery unit, provided at a downstream
side of a catalyst that cleans the exhaust gas, that recovers heat
from the exhaust gas.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 USC 119 from
Japanese Patent Application No. 2015-165730, filed on Aug. 25, 2015
the disclosure of which is incorporated by reference herein.
BACKGROUND
[0002] Technical Field
[0003] The present disclosure relates to an engine control
device.
[0004] Related Art
[0005] Japanese Patent Application Laid-Open (JP-A) No. 2006-161593
discloses an engine running mode that uses motive power from an
engine, an EV driving mode that uses motive power from a
motor-generator, and a hybrid running mode that uses motive power
from both the engine and the motor-generator. Further, it is
disclosed that, when a stop condition of the EV running mode is
encountered, an engine rotation speed is raised and engine noise
increases, which prompts a driver to perform a switching operation
to the engine running mode or the hybrid running mode.
[0006] In a vehicle equipped with this engine, if an external air
temperature is below freezing point and a preceding running
duration was short, condensed water that remains in an exhaust pipe
may freeze. Accordingly, in a case in which water is freezing in
the exhaust pipe, it is necessary to raise the engine rotation
speed in order to exhaust condensed water and melt ice in the
exhaust pipe. However, this happens with a different timing from
the stop condition of the EV running mode in JP-A No. 2006-161593.
Therefore, there is scope for improvement.
SUMMARY
[0007] The present disclosure provides an engine control device
that may promote drainage of condensed water and melting of frozen
water in an exhaust pipe.
[0008] An engine control device of a first aspect includes: an
adjustment section that adjusts a flow amount per unit time of
exhaust gas exhausted from an engine; and a control section that,
in a case in which a temperature below freezing point is detected
by a temperature detection section that detects an external air
temperature or an intake air temperature, a preceding engine
operation duration is shorter than a pre-specified first duration,
and a value in a predetermined range in which water in an exhaust
pipe can be drained by the flow amount being raised by a certain
amount is detected by a value detection section that detects a
value representing an acceleration, an accelerator opening or an
engine rotation speed, controls the adjustment section so as to
raise the flow amount by the certain amount until a pre-specified
second duration has passed from starting of the engine.
[0009] According to the above first aspect, the flow amount per
unit time of the exhaust gas exhausted from the engine is adjusted
by the adjustment section.
[0010] At the control section, in a case in which a temperature
below freezing point is detected by the temperature detection
section that detects an external air temperature or intake air
temperature, and in a case in which the preceding engine running
duration was shorter than the pre-specified first duration, and in
a case in which the value detection section that detects the value
representing an acceleration, an accelerator opening or an engine
rotation speed detects a value in the predetermined range in which
water in the exhaust pipe could be drained by the flow amount being
raised by the certain amount, then the control section controls the
adjustment section so as to raise the flow amount by the certain
amount until the pre-specified second duration has passed from the
engine starting. That is, in a case in which the temperature is
below freezing point, the preceding engine running duration was
short and the acceleration, accelerator opening or engine rotation
speed is in the predetermined range, freezing is likely to occur in
the exhaust pipe. Accordingly, drainage of condensed water and
melting of frozen water in the exhaust pipe may be promoted by the
control by the control section. Note, however, that in a situation
in which the acceleration is above the predetermined range and
drainage of condensed water is possible even without applying the
control to raise the flow amount, the control to raise the flow
amount is not performed.
[0011] A second aspect, in the above first aspect, the adjustment
section may adjust the flow amount per unit time of exhaust gas by
adjusting the engine rotation speed, the control section may
include a charging control section that, in a case in which a
charge amount of a battery, in a hybrid vehicle that is equipped
with an engine and a motor-generator as drive sources for running,
is below a pre-specified threshold, controls charging of the
battery such that the motor-generator is driven by motive power of
the engine and charges the battery, and the control section may
control the charging control section so as to charge the battery
with motive power corresponding to a rise in the engine rotation
speed that is produced by the control of the adjustment section to
raise the flow amount by the certain amount. Namely, motive power
that is produced as a result of the flow amount of exhaust gas
being raised by the certain amount is consumed by the charging
control section. Therefore, both deterioration in fuel consumption
may be prevented and an unintended acceleration due to the rise in
engine rotation speed may be prevented.
[0012] A third aspect, in the above second aspect, the charging
control section may end the charging of the battery in a case in
which the charge amount of the battery reaches at least a
pre-specified reference value, and the control section, in a case
in which adjusting the flow amount of exhaust gas, may alter the
reference value and control the charging control section. Thus, a
range in which both deterioration in fuel consumption and
prevention in unintended acceleration may be expanded.
[0013] A fourth aspect, in the above first aspect, the adjustment
section may adjust the flow amount per unit time of exhaust gas by
adjusting the engine rotation speed, and the control section may
control a consumption section that is for consuming motive power
corresponding to a rise in the engine rotation speed so as to
consume motive power corresponding to a rise in the engine rotation
speed that is produced by the control of the adjustment section.
Thus, an unintended acceleration due to the rise in engine rotation
speed may be prevented.
[0014] A fifth aspect, in the above aspects, may further include an
exhaust heat recovery unit, provided at a downstream side of a
catalyst that cleans the exhaust gas, that recovers heat from the
exhaust gas. Thus, exhaust heat may be recovered and utilized.
[0015] According to the above aspects, the present disclosure may
be provide an engine control device that may promote drainage of
condensed water and melting of frozen water in an exhaust pipe.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Exemplary embodiments will be described in detail based on
the following figures, wherein;
[0017] FIG. 1 is a block diagram showing schematic structures of an
engine control device in accordance with a present exemplary
embodiment;
[0018] FIG. 2 is a diagram for describing an exhaust heat recovery
unit;
[0019] FIG. 3 is a table showing conditions for detecting freezing
of condensed water in an exhaust pipe;
[0020] FIG. 4 is a flowchart showing a flow of processing that is
executed by an engine ECU of the engine control device in
accordance with the present exemplary embodiment;
[0021] FIG. 5 is a diagram for describing fuel consumption maps and
a water-blowing map that serve as P charging maps; and
[0022] FIG. 6 is a flowchart showing a flow of processing that is
executed by an engine ECU of an alternative example of the engine
control device in accordance with the present exemplary
embodiment.
DETAILED DESCRIPTION
[0023] Herebelow, an exemplary embodiment is described in detail
with reference to the attached drawings. FIG. 1 is a block diagram
showing schematic structures of an engine control device in
accordance with the present exemplary embodiment. Below, an engine
control device that is installed in a hybrid car is taken as an
example of the engine control device and described. The hybrid car
is equipped with an engine and a motor-generator as drive sources
for running.
[0024] An engine control device 10 according to the present
exemplary embodiment is equipped with an engine ECU (electronic
control unit) 12, which serve as a control section that controls
operations of the engine and as a charging control section. The
engine ECU 12 is constituted by a microcomputer including a central
processing unit (CPU), a read-only memory (ROM), a random access
memory (RAM) and the like.
[0025] Various sensors 14 for controlling operations of the engine
are connected to the engine ECU 12. The engine ECU 12 controls
operations of the engine on the basis of detection results from the
various sensors 14. The various sensors 14 that are connected
include an external air temperature sensor 16, a water temperature
sensor 18, an accelerator opening detection sensor 24, an intake
air temperature sensor 20, an exhaust temperature sensor 22, a
fuel-air ratio sensor 26, an intake air amount sensor 28, a crank
angle detection sensor 30, a vehicle speed sensor 32 and an
acceleration sensor 33. These various sensors 14 are an example and
the above description is not limiting. Any of the various sensors
14 may be omitted and alternative sensors may be included. The
external air temperature sensor 16 and intake air temperature
sensor 20 correspond to a temperature detection section, and the
accelerator opening detection sensor 24, crank angle detection
sensor 30 and acceleration sensor 33 correspond to a value
detection section.
[0026] The external air temperature sensor 16 detects external air
temperatures, the water temperature sensor 18 detects temperatures
of cooling water in the engine, the intake air temperature sensor
20 detects intake air temperatures, and the exhaust temperature
sensor 22 detects temperatures of exhaust gas. The accelerator
opening detection sensor 24 detects accelerator opening amounts,
the fuel-air ratio sensor 26 detects fuel-air ratios of exhaust gas
from the engine, the intake air amount sensor 28 detects air
amounts aspirated into the engine, the crank angle detection sensor
30 detects crank angles, and the vehicle speed sensor 32 detects
vehicle speeds.
[0027] For controlling operations of the engine, a throttle motor
34, an ignition device 36, a fuel injection device 38, a hybrid
vehicle (HV) driving distribution device 40 and a transmission
control device 42 are also connected to the engine ECU 12. The
throttle motor 34 drives a throttle that adjusts aspirated air
amounts to the engine in correspondence with an adjustment section.
Thus, the throttle motor 34 alters a throttle opening amount and
adjusts the engine rotation speed. The ignition device 36 generates
sparks required for commencing combustion of a fuel-air mixture
compressed in cylinders of the engine. The fuel injection device 38
supplies the fuel-air mixture into the cylinders of the engine by
injecting fuel. In response to a consumption section, the HV
driving distribution device 40 controls a driving distribution
between the engine and a motor-generator 44, which are drive
sources for running, and controls driving of the motor-generator
44. When starting of the engine is required, the HV driving
distribution device 40 outputs an engine start request to the
engine ECU 12. In response to the consumption section, the
transmission control device 42 controls a gear ratio of a
transmission in which the gear ratio can be altered (for example, a
continuously variable transmission or the like). The transmission
control device 42 includes a function for detecting gearshift
positions such as a reversing position and the like, and controls
alterations of the gear ratio at the transmission.
[0028] On the basis of detection results from the various sensors
14, the engine ECU 12 controls operations of the engine by
controlling the throttle motor 34, the ignition device 36, the fuel
injection device 38 and the like. The engine ECU 12 also controls
the driving distribution between the engine and the motor-generator
44, the transmission and the like in accordance with
circumstances.
[0029] In the present exemplary embodiment, a first motor-generator
44A and a second motor-generator 44B are provided to serve as the
motor-generator 44. The first motor-generator 44A principally
functions as a generator for charging a battery or as a generator
for supplying electric power to the second motor-generator 44B. The
first motor-generator 44A is powered by motive power from the
engine. The second motor-generator 44B principally functions as a
generator that supplements power output from the engine. Although
two motor-generators are provided in the present exemplary
embodiment, there may be a single motor-generator.
[0030] An exhaust heat recovery unit is provided in the vehicle in
which the engine control device 10 according to the present
exemplary embodiment is installed. FIG. 2 is a diagram for
describing the exhaust heat recovery unit.
[0031] An exhaust heat recovery unit 58 is provided on an exhaust
pipe 60 through which exhaust gas of the automobile passes. The
exhaust heat recovery unit 58 recovers heat from the exhaust gas
from the engine of the automobile and utilizes the heat for
heating, promoting engine warm-up and the like.
[0032] For example, as shown in FIG. 2, an exhaust path of the
exhaust pipe 60 exhausts exhaust gas from an engine 50, and a
catalytic device 56, the exhaust heat recovery unit 58 and a main
muffler 62 are arranged in this order from upstream on the exhaust
path.
[0033] The exhaust heat recovery unit 58 is provided at the
downstream side of the catalytic device 56 and recovers heat from
the exhaust gas. To be specific, cooling water for cooling the
engine 50 is circulated to the exhaust heat recovery unit 58 by a
water pump (W/P) 52. Cooling water that is circulated to the
exhaust heat recovery unit 58 flows through a heater core 54 and is
returned to the engine 50. That is, the exhaust heat recovery unit
58 is provided on a flow path of the cooling water; heat in the
exhaust gas may be recovered by the exhaust heat recovery unit 58,
may raise the temperature of the cooling water, and may be utilized
as a heat source for a heater. In this structure, the water pump 52
of an electric type that is driven by a motor or the like, is
employed. Thus, a flow amount of cooling water flowing through the
exhaust heat recovery unit 58 may be varied, and recovered amounts
of exhaust heat may be adjusted by adjustment of the flow amount of
cooling water flowing through the exhaust heat recovery unit
58.
[0034] Now, in a vehicle that is running with the engine 50, if
condensed water is produced in the exhaust pipe 60 and falls below
freezing point without being exhausted, the water may freeze. If
condensed water freezes inside the exhaust pipe 60, depending on
running conditions, it is possible that the water may not be melted
but remains in the exhaust pipe 60. If the condensed water remains
in the frozen state and more condensed water is produced and
freezes, exhaust performance may deteriorate, which may lead to a
loss of engine output power, a worsening of exhaust noise within
the vehicle and suchlike. In particular, in a vehicle that is a
hybrid vehicle and that is equipped with the exhaust heat recovery
unit 58 as in the present exemplary embodiment, condensed water is
easily produced because of the engine stopping during running.
Furthermore, the exhaust pipe 60 is provided with differences in
height thereof as shown in FIG. 2, in order to avoid other
components. Consequently, condensed water is unlikely to be drained
to the rear unless the flow speed of the exhaust gas (i.e., the
engine rotation speed) is at least a certain level.
[0035] Accordingly, in the present exemplary embodiment, the engine
ECU 12 performs control to raise the flow amount per unit time of
the exhaust gas by a certain amount in order to drain condensed
water and melt frozen water inside the exhaust pipe 60. The control
to raise the flow amount of the exhaust gas is, specifically, that
if pre-specified conditions with which freezing inside the exhaust
pipe 60 is anticipated are met, the engine ECU 12 controls the
throttle motor 34 so as to raise the engine rotation speed higher
than in a pre-specified usual state. However, condensed water
drainage performance, ice melting performance and the like vary
depending on engine specifications (for example, exhaust amounts,
compression ratio, exhaust port diameters and the like), and on the
diameter of the exhaust pipe 60 and so forth. Therefore, the extent
to which the flow amount is raised is specified in advance in
accordance with engine specifications, the diameter of the exhaust
pipe 60 and so forth. For example, a flow amount per unit time to
which the exhaust gas flow amount is to be raised, at which
condensed water may be drained and ice may be melted, is specified
in advance in accordance with at least one of the engine
specifications and the diameter of the exhaust pipe. An idling
state after the end of a warm-up operation may be employed as the
pre-specified usual state. Alternatively, an idling state that
incorporates an engine control state (for example, a warm-up
operation or the like) in which the flow amount of exhaust gas is
raised by the engine rotation speed being raised in accordance with
various corrections, such as a correction for external air
temperature, a correction for water temperature, a correction for
air pressure and the like, may be employed. Alternatively again, an
operation state with a pre-specified engine rotation speed
corresponding to an accelerator opening may be employed. The
control by the engine ECU 12 to raise the flow amount of exhaust
gas by the certain amount differs from control of a warm-up
operation when cold is sensed. Moreover, although the engine
rotation speed rises with vehicle speed, the control to raise the
flow amount of exhaust gas includes control to increase the engine
rotation speed further beyond a pre-specified level.
[0036] Conditions for detecting freezing of condensed water inside
the exhaust pipe 60 may be, for example, conditions (1) to (3)
shown in FIG. 3. Further, the flow amount of exhaust gas may be
raised when supplementary conditions (4) to (8) apply in addition
to conditions (1) to (3).
[0037] (1) When the external air temperature is below freezing
point (0.degree. C. or less), that is, when the external air
temperature is a temperature at which condensed water in the
exhaust pipe 60 freezes, the flow amount of exhaust gas is to be
raised and condensed water and ice are to be exhausted.
[0038] (2) When an engine operation duration after starting of the
engine is less than a predetermined duration (for example, 10
minutes), that is, a state prior to melting of any ice that has
formed since a preceding run, the exhaust gas flow amount is to be
raised for exhausting ice in order to prevent further deposition of
ice. This duration may be substituted with a measurement that
corresponds to the duration after the engine starting, of a
gasoline consumption amount, a temperature of the cooling water, a
number of successive rotations since the engine starting, or the
like. A further predetermined duration after starting that is
employed is a duration that is specified in advance in accordance
with engine specifications and the diameter of the exhaust pipe 60,
because produced heat amounts vary in accordance with engine
specifications (for example, exhaust amounts, compression ratio,
exhaust port diameters and the like), the diameter of the exhaust
pipe 60 and so forth.
[0039] (3) In a state in which a preceding engine operation
duration was less than a continuous predetermined duration (for
example, 10 minutes) and ice from a run before the preceding run
has not melted (a state in which ice worth of two operation cycles
has deposited), the exhaust gas flow amount is to be raised and the
ice is to be melted and exhausted. Because produced heat amounts
vary depending on engine specifications, the diameter of the
exhaust pipe 60 and the like, the predetermined duration that is
employed is a duration specified in advance in accordance with the
engine specifications and the diameter of the exhaust pipe 60.
[0040] (4) In addition to conditions (1) to (3), if control is
performed to raise the rotation speed for an interval of several
seconds once each several minutes (the engine rotation speed is
intermittently raised for a pre-specified duration at pre-specified
time intervals), condensed water is not always continuously
exhausted; instead, condensed water deposit to some extent and is
then exhausted.
[0041] (5) If condensed water is exhausted while the vehicle is
parked, the condensed water soils a parking space such as a garage
or the like. Therefore, in addition to conditions (1) to (3), if
the vehicle speed is at least a predetermined vehicle speed (for
example, 10 km/h), condensed water is exhausted during running. The
predetermined vehicle speed is a vehicle speed indicating that
running has started; it is not limited to 10 km/h.
[0042] (6) In addition to conditions (1) to (3), if a maximum Ga
(corresponding to a maximum aspirated air amount, a maximum engine
rotation speed or the like) since the start of control to raise the
rotation speed exceeds a predetermined value (for example, 10 g/s),
the control stops for several minutes (for example, 3 minutes) and
subsequently restarts. That is, if the aspirated air amount exceeds
a pre-specified air amount during running and the exhaust gas flow
amount is high, the control to raise the rotation speed is
unnecessary and is stopped. Thus, a deterioration in fuel
efficiency is avoided.
[0043] (7) In addition to conditions (1) to (3), if the gearshift
is in the reversing (R) range, then, given that there are no
obstacles or people to the rear, draining water will not strike a
person. Accordingly, the flow amount of exhaust gas is raised and
condensed water and ice are exhausted.
[0044] (8) Conditions (4) to (7) are combined in addition to
conditions (1) to (3). The above-described conditions (4) to (7)
may be combined with conditions (1) to (3) as appropriate.
[0045] That is, in the present exemplary embodiment, if the
external air temperature is below freezing point, and if the
preceding engine operation duration was shorter than a
pre-specified first duration, and if acceleration is in a
predetermined range (between a first acceleration and a second
acceleration), then the above-described control to raise the flow
rate of exhaust gas is applied until a pre-specified second
duration has passed from the starting of the engine. The
predetermined range of accelerations is a pre-specified range of
low accelerations, which are accelerations in a range specified in
advance in which condensed water is not exhausted by flow rates of
exhaust gas but which are accelerations in a range in which
condensed water inside the exhaust pipe 60 may be drained by the
flow rates of exhaust gas being raised. That is, the first
acceleration of the predetermined range is an acceleration at which
condensed water may be drained by the flow rate of exhaust gas
being raised by a certain amount, and the second acceleration is an
acceleration at which condensed water may be drained without the
flow rate of exhaust gas being raised. Because this predetermined
range of accelerations is included in the conditions, unnecessary
control may be suppressed and a deterioration in fuel efficiency
may be avoided.
[0046] An accelerator opening detected by the accelerator opening
detection sensor 24 or an engine rotation speed detected by the
crank angle detection sensor 30 may be employed instead of the
acceleration. That is, the conditions for raising the flow rate of
exhaust gas that are employed may be: that the temperature is below
freezing point, the preceding engine operation duration was shorter
than the predetermined duration and the accelerator opening is in a
predetermined range; that the temperature is below freezing point,
the preceding engine operation duration was shorter than the
predetermined duration and the rotation speed is in a predetermined
range; or the like.
[0047] A control method for raising the flow amount of exhaust gas
is control that raises the engine rotation speed in the present
exemplary embodiment, but may be control to charge a battery that
charges electric power to be supplied to the second motor-generator
44B (below referred to as P charging control). The meaning of the
term "P charging control" includes control to drive the first
motor-generator 44A with motive power from the engine and charge
the battery. More specifically, if a charge amount SOC of the
battery is below a minimum value (a threshold) .alpha.min of a
target region .alpha., then if the engine has been stopped, the
engine is started, and if the engine has been started, the engine
rotation speed is raised. Hence, the first motor-generator 44A is
driven by motive power from the engine and the battery is charged.
If the charge amount SOC is above a maximum value .alpha.max of the
target region .alpha., the engine ECU 12 controls the HV driving
distribution device 40 so as to end charging. That is, the flow
rate of exhaust gas may be raised by the certain amount by the
engine ECU 12 controlling the HV distribution device 40 and
performing P charging control. Here, when the flow rate of exhaust
gas is raised by P charging control, the maximum value.alpha.max of
the target region .alpha. of the charge amount SOC, which serves as
a reference value for ending charging, is altered. For example, if
charging is usually ended when the charge amount is 60%, the
reference value for ending charging may be raised and altered such
that charging is ended at 80% or the like. As a result, the range
of P charging control may be expanded and a deterioration in fuel
efficiency may be avoided.
[0048] Now, specific processing that is carried out by the engine
ECU 12 of the engine control device 10 relating to the present
exemplary embodiment structured as described above is described.
FIG. 4 is a flowchart showing an example of a flow of processing
that is executed by the engine ECU 12 of the engine control device
10 according to the present exemplary embodiment. The processing in
FIG. 4 starts when the engine ECU 12 receives an engine start
request outputted from the HV driving distribution device 40.
[0049] In step 100, the engine ECU 12 starts the engine, and then
proceeds to step 102.
[0050] In step 102, the engine ECU 12 makes a determination as to
whether an external air temperature is 0.degree. C. or less from a
detection result of the external air temperature sensor 16. If the
result of the determination is affirmative, the engine ECU 12
proceeds to step 104, and if the result is negative, the engine ECU
12 ends the sequence of processing. The determination in step 102
may be a determination as to whether an intake air temperature is
0.degree. C. or less instead of the external air temperature.
[0051] In step 104, the engine ECU 12 makes a determination as to
whether a preceding engine operation duration (an ENG ON duration)
was at least a predetermined duration (for example, 10 minutes).
This determination is made by the preceding engine operation
duration having been memorized at the engine ECU 12. If the result
of this determination is negative, the engine ECU 12 proceeds to
step 106, and if the result of the determination is affirmative,
the engine ECU 12 ends the sequence of processing. The engine ECU
12 stops the engine when an ignition switch, which is not shown in
the drawings, is turned OFF or when the engine ECU 12 receives an
engine stop request. The term "engine operation duration" may refer
to an integrated value Ga of exhaust gas flow amounts calculated
from aspirated air amounts, engine rotation speeds or the like.
[0052] In step 106, the engine ECU 12 makes a determination as to
whether the acceleration is in the predetermined range from a
detection result from the acceleration sensor 33. If the result of
this determination is affirmative, the engine ECU 12 proceeds to
step 108, and if the result is negative, the engine ECU 12 returns
to step 102 and repeats the processing described above.
[0053] In step 108, the engine ECU 12 starts control to raise the
engine rotation speed (the exhaust gas flow amount) and then
proceeds to step 110. For example, the engine ECU 12 raises the
flow amount of exhaust gas by driving the throttle motor 34 to
raise the engine rotation speed by the certain amount. As a result,
condensed water and ice in the exhaust pipe 60 are exhausted.
However, an unintended acceleration may result from raising the
engine rotation speed of an engine. Therefore, for example, the
driving distribution between the engine and the second
motor-generator 44B may be controlled by the HV driving
distribution device 40 and motive power that is produced by the
raising of the engine rotation speed may be consumed, which may
prevent an unintended acceleration. Alternatively, the gear ratio
may be altered by control of the transmission control device 42 and
motive power that is produced by the raising of the engine rotation
speed may be consumed, which may prevent an unintended
acceleration. As a further alternative, the engine ECU 12 may
control the HV driving distribution device 40 so as to switch to P
charging control and drive the first motor-generator 44A with
motive power corresponding to the raising of the engine rotation
speed, which may cause the motive power produced by the raising of
the engine rotation speed to be consumed by charging of the battery
and prevent an unintended acceleration. In a case of switching to P
charging control, as described above, the value of .alpha.max that
serves as the reference value for stopping P charging control is
changed to a larger value than usual. Alternatively, the engine ECU
12 may perform control that combines these measures as appropriate
so as to consume the motive power corresponding to the raising of
the engine rotation speed. This control to raise the engine
rotation speed, rather than being performed continuously, may be
performed, for example, intermittently for only a few seconds once
each several minutes.
[0054] In step 110, the engine ECU 12 makes a determination as to
whether at least a predetermined duration (for example, 10 minutes)
has passed from the starting of the engine. If the result of this
determination is negative, the engine ECU 12 proceeds to step 112,
and if the result is affirmative, the engine ECU 12 proceeds to
step 120.
[0055] In step 112, the engine ECU 12 makes a determination as to
whether a maximum Ga (the maximum aspirated air amount, maximum
engine rotation speed or the like) since the start of control to
raise the engine rotation speed exceeds a predetermined value (for
example, 10 g/s). If the result of this determination is
affirmative, the engine ECU 12 proceeds to step 114, and if the
result is negative, the engine ECU 12 returns to step 110 and
repeats the processing described above.
[0056] In step 114, the engine ECU 12 stops the control to raise
the engine rotation speed (the exhaust gas flow amount), and then
proceeds to step 116.
[0057] In step 116, the engine ECU 12 makes a determination as to
whether a predetermined duration (for example, 3 minutes) has
passed since the stopping of the control to raise the engine
rotation speed. The engine ECU 12 waits until the result of this
determination is affirmative, and then proceeds to step 118.
[0058] In step 118, the engine ECU 12 restarts the control to raise
the engine rotation speed, and then returns to step 110 and repeats
the processing described above. That is, if the exhaust gas flow
amount rises during running, control to raise the rotation speed is
unnecessary, so is temporarily stopped and is restarted after a
predetermined duration has passed.
[0059] On the other hand, in step 120, if the engine ECU 12 is
performing control to raise the engine rotation speed, the engine
ECU 12 stops the control and ends the sequence of processing. When
stopping the control to raise the engine rotation speed, the engine
ECU 12 returns to the pre-specified usual state gradually so as not
to cause disturbance to vehicle occupants.
[0060] Thus, by performing control to raise the engine rotation
speed, the engine ECU 12 may promote drainage of condensed water
and melting of frozen water in the exhaust pipe 60.
[0061] Now, an alternative example of the engine control device
according to the present exemplary embodiment is described. In this
alternative example, P charging is utilized as control for raising
the flow amount of exhaust gas, so as to raise the flow amount of
exhaust gas. Basic structures are the same as in the exemplary
embodiment described above, so are not described in detail
here.
[0062] In the alternative example, if the external air temperature
is below freezing point, the preceding engine operation duration
was shorter than a predetermined duration, and the acceleration is
in a predetermined acceleration range, a P charging map is altered
to raise the flow amount of exhaust gas by a certain amount.
[0063] To be specific, pre-specified fuel consumption maps for
maximizing efficiency and a water-blowing map for exhausting
condensed water are provided to serve as a P charging map, and the
flow amount of exhaust gas is raised by switching the P charging
map. The water-blowing map is a map configured such that .alpha.max
of the charge amount SOC at which charging stops is changed to a
larger value and such that P charging control is switched to in the
predetermined acceleration range described in the exemplary
embodiment above.
[0064] As shown in FIG. 5, where the fuel consumption map (without
P charging) is a map that produces gas flow amounts that may drain
condensed water at accelerations above the second acceleration, the
water-blowing map is a map that enables drainage of condensed water
in the predetermined range of accelerations by performing P
charging control. In the fuel consumption map (without P charging)
shown in FIG. 5, water would not be drained out below the first
acceleration even if P charging control were performed, and water
is drained out above the second acceleration even if P charging
control is not performed. Therefore, P charging control is
unnecessary in these regions. Accordingly, in the water-blowing map
P, charging control is performed only in the region of the
predetermined range of accelerations.
[0065] In this alternative example, because the water-blowing map
is used to switch to P charging control when acceleration is in the
predetermined range during progressive acceleration, both drainage
of condensed water and fuel efficiency may be achieved. "With P
charging" in FIG. 5 indicates maximum values of Ga determined in
consideration of noise and the like, which are set appropriately in
accordance with the type of vehicle and the like. Although the
engine rotation speed is raised by the P charging control, power
corresponding to this rise is consumed in charging of the battery.
Therefore, deterioration in fuel efficiency may be prevented and an
unintended acceleration may be prevented.
[0066] In this alternative example, the reference value for ending
charging of the battery is altered when the water-blowing map is
switched to, as described in the above exemplary embodiment.
Therefore, a range in which both deterioration in fuel efficiency
and prevention in unintended acceleration, may be expanded.
[0067] In the alternative example too, as described for the
exemplary embodiment above, an accelerator opening detected by the
accelerator opening detection sensor 24 or an engine rotation speed
detected by the crank angle detection sensor 30 may be employed
instead of the acceleration. That is, a map such that P charging
control is switched to in a predetermined range of accelerator
openings or rotation speeds may be employed as the water-blowing
map.
[0068] Now, specific processing that is carried out by the engine
ECU 12 of the engine control device 10 relating to the alternative
example is described. FIG. 6 is a flowchart showing an example of a
flow of processing that is executed by the engine ECU 12 of the
engine control device 10 according to the alternative example. The
processing in FIG. 6 starts when an ignition switch (IG), which is
not shown in the drawings, is turned ON.
[0069] In step 200, the engine ECU 12 makes a determination from
detection results of the intake air temperature sensor 20 as to
whether intake air temperatures at times of the IG being turned on
a preceding time and the present time are 0.degree. C. or less. If
the result of this determination is affirmative, the engine ECU 12
proceeds to step 202, and if the result is negative, the engine ECU
12 ends the sequence of processing. The determination of step 200
may be a determination as to whether, as in the exemplary
embodiment described above, the external air temperature is
0.degree. C. or less instead of the intake air temperature.
[0070] In step 202, the engine ECU 12 reads a preceding integrated
value of Ga, and then proceeds to step 204.
[0071] In step 204, the engine ECU 12 makes a determination as to
whether the preceding engine operation duration (ENG ON duration)
was at least a predetermined duration (for example, 10 minutes).
This determination is made by the preceding engine operation
duration having been memorized at the engine ECU 12. If the result
of this determination is negative, the engine ECU 12 proceeds to
step 206, and if the result is affirmative, the engine ECU 12 ends
the sequence of processing. An integrated value Ga of exhaust gas
flow amounts that is calculated from aspirated air amounts, engine
rotation speeds or the like may be employed as the engine operation
duration.
[0072] In step 206, the engine ECU 12 makes a determination as to
whether Ga (the aspirated air amount, engine rotation speed or the
like) is less than a pre-specified value a. If the result of this
determination is negative, the engine ECU 12 proceeds to step 208,
and if the result is affirmative, the engine ECU 12 proceeds to
step 214.
[0073] In step 208, the engine ECU 12 makes a determination as to
whether the P charging map has been changed. This determination is
a determination as to whether the P charging map has been changed
to the water-blowing map in step 218, which is described below. If
the result of the determination is affirmative, the engine ECU 12
proceeds to step 210, and if the result is negative, the engine ECU
12 returns to step 202 and repeats the processing described
above.
[0074] In step 210, the engine ECU 12 makes a determination as to
whether the state in which Ga is less than a (the aspirated air
amount or engine rotation speed is at a level at which the flow
amount of exhaust gas is small and condensed water is not being
exhausted) has continued for more than several seconds (for
example, 3 s). If the result of this determination is affirmative,
the engine ECU 12 proceeds to step 212, and if the result is
negative, the engine ECU 12 returns to step 202 and repeats the
processing described above.
[0075] In step 212, the engine ECU 12 restores the P charging map
(switches to the fuel efficiency map), resets the integrated values
of Ga (the preceding and current integrated values of Ga), and then
returns to step 202 and repeats the processing described above.
[0076] Alternatively, in step 214, the engine ECU 12 adds the
preceding integrated value of Ga that has been read to the current
integrated value of Ga, and then proceeds to step 216.
[0077] In step 216, the engine ECU 12 makes a determination as to
whether the calculated integrated value of Ga is at least a
pre-specified value b. That is, the engine ECU 12 makes a
determination as to whether Ga continues to be small and a
deposition amount of water has gone above a pre-specified value. If
the result of the determination is affirmative, the engine ECU 12
proceeds to step 218 in order to raise the flow amount of exhaust
gas, and if the result is negative, the engine ECU 12 proceeds to
step 220.
[0078] In step 218, the engine ECU 12 changes the P charging map
from the fuel efficiency map to the water-blowing map, and then
proceeds to step 220. As a result, as shown in FIG. 5, the flow
amount of exhaust gas is raised in the predetermined range of
accelerations, and drainage of condensed water and melting of
frozen water in the exhaust pipe 60 may be promoted.
[0079] In step 220, the engine ECU 12 makes a determination as to
whether the ignition switch (IG) that is not shown in the drawings
has been turned OFF. If the result of the determination is
negative, the engine ECU 12 returns to step 206 and repeats the
processing described above, and if the result is affirmative, the
engine ECU 12 ends the sequence of processing.
[0080] Thus, in the alternative example, P charging control is
performed when the external air temperature is below freezing
point, the preceding engine operation duration is shorter than a
predetermined duration, and the acceleration is in the
predetermined acceleration range. Thus, the flow amount of exhaust
gas may be raised and condensed water in the exhaust pipe 60 may be
exhausted.
[0081] Moreover, condensed water may be exhausted efficiently by
switching to P charging control during progressive
acceleration.
[0082] Because P charging control is performed when in the
predetermined range of accelerations, motive power for running is
charged in the battery. Therefore, deterioration in fuel efficiency
may be kept to minimum. Furthermore, because the motive power
corresponding to the raising of the engine rotation speed is
consumed by charging of the battery in accordance with the P
charging control, an unintended acceleration caused by the raising
of the engine rotation speed is prevented, and a disturbance of
vehicle occupants by the raising of the engine rotation speed may
be moderated.
[0083] In the exemplary embodiment described above, an example is
described in which control is performed to raise the flow amount of
exhaust gas by raising the engine rotation speed. However, control
for raising the flow amount of exhaust gas is not limited thus. The
flow amount of exhaust gas may be raised without raising the engine
rotation speed by, for example, the throttle motor 34 being driven
to widen the throttle opening and increase aspirated air amounts
and the ignition device 36 being controlled to delay ignition
timings.
[0084] In the exemplary embodiment and alternative example
described above, a hybrid vehicle is given as an example and
described, but the hybrid vehicle is not limiting. For example, the
present disclosure may be applied to a vehicle that runs with only
an engine.
[0085] In the exemplary embodiment and alternative example
described above, a vehicle that is equipped with the exhaust heat
recovery unit 58 is described as an example, but it will be clear
that the present disclosure is applicable to a vehicle that is not
equipped with the exhaust heat recovery unit 58.
[0086] The processing that is executed by the engine ECU 12
according to the exemplary embodiment and alternative example
described above may be software processing that is implemented by a
computer executing a program, and the processing may be implemented
in hardware. Alternatively, the processing may combine both
software and hardware. Further, if the processing is implemented in
software, the program may be memorized in any of various storage
media and distributed.
[0087] The present disclosure is not limited by the above
recitations. In addition to the above recitations, it will be clear
that numerous modifications may be embodied within a technical
scope not departing from the gist of the disclosure.
* * * * *